Safety bomb for submarine blasting



1941 w. B. ALFORD 2,262,445-

' SAFETY BOMB FOR SUBMARINE BLASTING Filed April 26, 1939 2 Shee(.s-Sheet l Q4 #016 INVENTOR.

A TTORNEY New. 111, 1941, w. B. ALFORD SAFETY BOMB FOR SUBMARI NEBLAS'IING.

v Filed April 26, 1939 2 Sheets-Sheet 2 Defend/927 M? ig. Z

IN V EN TOR.

A TTORNEYS.

Patented Nov. ll, 124i UNE?E@ STAT S PAT I; GFFEQE SAFETY norm FOESUBMARINE BLASTHG Application April 26, 1939, Serial No. 270,145

4 Claims.

The present invention relates to the art of submarine blasting and, inparticular, to a safety blasting assembly especially adapted tosubmarine demolition operations.

The large scale flood control operations recently undertaken by the U.S. Government have done much to emphasize the importance of submarineblasting operations and to call attention to the many hazards involvedtherein.

Among the many practical problems involved in these and other relatedsubmarine blasting operations may be listed the demolition and removalof sunken boats, the removal of concrete or wooden pilings, the breakingup of log jams, the demolition of bridge piers, the shooting of newcut-offs on the river, the removal of shale and shell beds in tidalwater, the shooting of river crossings for pipe lines and oil feeds, theremoval of fallen trees from river banks, the making of boat landings inthe marsh, and the like. For these and other submarine blastingoperations, the blasting assemblies heretofore known, have many defectsand disadvantages. This is especially true from the standpoint of safetyand certainty of successful shooting. For instance, operators in thefield of submarine blasting know how difilcult it is to drop a case orbundle of dynamite on a sunken barge, particularly in a current flowingfrom 10 to 13 feet a second.

The object of my invention is a new and improved safety blastingassembly especially adapted to submarine blasting operations. Furtherobjects will be apparent from the following detailed description of myinvention.

I have found that these objects may be accomplished and thedisadvantages overcome by means of the safety submarine blastingassembly of my invention, also referred to by me as a snag grapnelsafety bomb. My submarine blasting assembly or bomb comprises containingmeans for retaining the explosive, means for attaching a towing cablewhereby the bomb may be towed along under the surface of the water, andgrapnel means for fastening said bomb into place against the submergedobject which is being blasted.

The containing means for retaining the ex plosive may be in the form ofa single water-tight metal container, or it may take the form of a rigidframework adapted to support and retain one or more units of cannedexplosives. Although any blasting explosive may be employed in mydevice, I find that remarkably superior results may be obtained from thestandpoint of safety in submarine blasting by using explosives whichhave a sensitiveness of no greater order of magnitude than that oftrinitrotoluene. Among the explosives of this type, to which I willhereinafter refer as "safety explosives, I may list: trinitrotoluene,pentaerythritol tetranitrate, certain picrates, comparativelyinsensitive compositions comprising ammonium nitrate sensitized witharomatic hydrocarbons and the like, and similar explosives within theforegoing sensitiveness range. It is desirable, of course, to employ atleast a primer charge which is sensitive to a commercial blasting capand to a commercial detonating fuse.

It should be understood, however, that while it is highly advantageousto employ water-tight metal containers for many of these explosives,especially those containing appreciable amounts of ammonium nitrate, myinvention is not limited to such an assembly. Instead, I may employcertain explosives having a high degree of water resistance such asgelatin dynamites, for example. These could be employed withoutnecessitating a water-proof container for the explosive.

The details of my invention may be more readily appreciated by referringto the accompanying drawings which disclose preferred embodimentsthereof, but which are not to be taken as limiting the scope of theinvention.

Referring generally to the several views of the drawings, Figure l is aview of my safety bomb being employed to blast a log jam. Figure 2 is aview in vertical elevation of a preferred embodiment of my safety bomb.Figure 3 is a section of Figure 2 taken through the region AA. Figure 4is a view in vertical elevation of the retaining frame with grapnelsattached. Figure 5 is a plan view of the same.

Referring in greater detail to the various figures of the drawings, thepreferred embodiment of my invention, as shown in Figure 4, comprisesthe steel frame consisting of the central bar I, preferably of seamlesssteel mechanical tubing and the supporting base 2. Mounted on either orboth ends of the central bar are the grapnels 3. Four cans of explosive5 are placed on the base, grouped about the central bar. These cans areheld in place by means of steel bands 6 and l clamped about the top andbottom of the cans, as shown in Figure 2. Preferably one can contains abooster charge and serves as the primer. This primer can is providedwith the confining tunnel 8' adapted to retain a length of detonatingfuse 9 against the side of the can. This length of fuse preferablyextends upward out of the water to a blasting cap, as indicated by thelegends in Figure 2. The central bar is provided with a drill hole l atits upper end for fastening thereto a towing cable II which may be heldin the form of a loop by the clips l8.

The device when assembled with towing cable and a length of cap fuse,attached as indicated, is submerged beneath the surface of the water andtowed along thereunder by any suitable means; for example, by means ofthe tow-boat i3 shown in Figure 1. Finally, the grapnels hook into thelog jam or other obstruction I4, as shown. Then, it is time to shoot. InFigure 1, the grapnels are shown disposed at the lower end of the bombin a position inclined toward the upper end. However, they may be placedat either or both ends of the bomb.

Although I have described my invention in the foregoing with particularreference to initiation by means of a detonating fuse and cap, it shouldbe understood that my invention is not limited thereto. For instance,under some conditions, I may employ an electric blasting cap of theconventional type, with leg wires of sufficient length to meet theoperating conditions.

More generally, it is found that the log jam has started from thekey-log leaning up against some old, submerged stump, bridge pier, orthe like. In this case, the bomb'can be pulled up stream until it isfastened close to this obstruction, and then set off. If the entire jamdoes not move with this first shot, I then continue to work upstream,and in this Way all debris moves downstream until it clears the entirechannel.

Alternatively, the bomb can be used in what I would call a strung shot,making the first one with a nose turned up to protect it, and keeping itfrom hanging up on the bottom; and the other sections made withoutgrapnels, making them plain so that as many as from 100 to 200 linearfeet can be made. It can be dropped overboard and pulled upstream untilit straightens out and reaches the exact place where the shot is to bemade.

The bomb can be used for removing large stumps sitting or hanging on theriver banks by throwing the cable over the outside of the stump andpulling the bomb until it hooks itself under the inside, assuming thechannel is pretty well filled with water as it is in most cases in riverwork.

I have been given to understand, by those employed in flood-controloperations, that the bomb of my invention has contributed greatly to theincreased safety of these operations, since less shots are misplacedunder water, and for the reason that the bomb is, in its preferred form,charged with such safety explosives as to render it innocuous if it ismisplaced or lost under water, since it is practically impossible to setit oif by shock alone. Accordingly, it is to all practical purposesrelatively harmless if it breaks away from the capped portion of thefuse, which is maintained above the water where it can be kept in sight.

It should be understood, of course, that the foregoing descriptionrefers to only a preferred embodiment of my invention. Many variationscan be made without departing from the scope of the invention. Forinstance, the grapnels could be attached to a single large container ofexplosive instead of having four separate cans, or

be bound only by the following patent claims.

I claim:

1. A safety blasting assembly especially adapted to submarine blasting,which comprises a central bar, a supporting frame attached to the lowerend of said bar, four water-tight containers resting on said frame andretained about said bar, said containers being charged with a safetyexplosive, at least one of said containers including a booster charge, alength of commercial detonating fuse in initiating relationship withsaid booster charge, means disposed at the upper end of said bar forattaching a tow line thereto, and grapnel means disposed at an end ofsaid bar.

2. A safety blasting assembly especially adapted to submarine blasting,which comprises a central bar, a supporting frame attached to the lowerend of said bar, four water-tight containers resting on said frame andretained about said bar, said containers being charged with a safetyexplosive, at least one of said containers including a booster chargeand having a confining tunnel adapted to retain a length of commercialdetonating fuse therein, means disposed at the upper end of said bar forattaching a tow line thereto. and grapnel means disposed at an end ofsaid bar.

3. A safety blasting assembly especially adapted to submarine blasting,which comprises a central bar, a supporting base attached to the lowerend of said bar, a plurality of water-tight'containers charged withblasting explosive resting on said frame and retained adjacent to saidbar at least one of said containers including a booster charge and beingprovided with a tunnel adapted to retain a length of commercialdetonating fuse in initiating relationship with said booster charge,means at the upper end of said bar for attaching a tow-line thereto, andgrapnel means disposed at at least one end of said bar.

4. A safety blasting assembly especially adapted to submarine blasting,which comprises a central bar, a supporting frame attached to the lowerend of said bar, a container charged with gelatin dynamite, saidcontainer resting on said frame and retained about said bar and beingprovided with means for retaining a water-impervious initiator adjacentto said gelatin dynamite, means at one end of said bar for attaching atowing cable, and grapnel means for snagging a submerged object.

WALTER BOSWELL ALFORD

